Genetic Improvement of Three Strains of Heterobranchus longifilis (Valenciennes, 1840) for Enhanced Food Security and Poverty Alleviation in Nigeria.

SIAR-Global Journal of Engineering & Agricultural Review(GJEAR) www.siarpublications.org [email protected] Vol. 1 Issue 1 Sept.-Oct. 2025 52 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. Genetic Improvement of Three Strains of Heterobranchus longifilis (Valenciennes, 1840) for Enhanced Food Security and Poverty Alleviation in Nigeria. Dr. John Unongo Technical Education Department, College of Education Oju, Benue State, Nigeria [email protected] Dr. Raphael Agbo Alih Department of Agricultural Science Education, College of Education Oju, Benue State, Nigeria raphae[email protected] Abstract This study was designed for genetic improvement of African Catfish, Heterobranchus longifilis, for enhanced food security and poverty alleviation in Nigeria, through intraspecific hybridization of germplasm from three eco-regions of Nigeria. Sexually mature species of the fish were collected from the wild; Guinea Savanna (Benue River, Makurdi, MK), Rainforest (Niger River, Onitsha, ON) and Sahel Savanna (Rima River, Sokoto,SK). Sex ratio of female to male was 2:1. They were transported to the Coordinating Institution, College of Education, Oju, and acclimatized in earthen ponds for 14 days. Nine mating combinations were attempted in a bid to improve the performance of the progenies. Growth and survival were then monitored for two and a half months (75 days). The progenies of the various mating combinations were further reared in earthen ponds to sexual maturity for a period of nine months (270 days). During this period, their weights and gonads were examined monthly, and in order to determine the true commercial application of the intraspecific crosses, growth performance was evaluated based on mean weight gain, mean final weight and specific growth rate. The hatchlings of the various mating combinations were initially reared indoors for two weeks and later transferred outdoors for 56 days during which length and weight data were collected. Of the nine mating combinations in this study, the highest percentage hatchability was recorded in the pure line crosses; Sokoto, Makurdi and Onitsha strains (85%) while the least was recorded for the intraspecific cross between female Onitsha and male Makurdi (♀ON x ♂ MK:63%). However, the intraspecific hybrids had higher survival rates than pure line hybrids. Growth performance of fry of the various mating combinations reared indoors for two weeks showed that the growth rates of the cross breeds were significantly higher than the pure breeds. The cross breed ♀MK x ♂ON had the highest weight gain (0.88 ± 0.00g) while ♂SK x ♂SK had the least weight gain (0.56 ± 0.00g). The growth parameters of the progenies reared outdoors in hapas for 56 days showed that the cross breed ♀MK x ♂SK had the highest mean final weight (1.560± 0.06g), mean weight gain of 1.450 ± 0.06g and specific growth rate of 0.047 ± 0.00g. At sexual maturity, all the cross breeds had higher mean final weights than their corresponding pure breeds; ♀MK x ♂SK(700g), ♀MK x ♂ON(653g) and ♀MK x ♂MK(615g), ♀ON x ♂ SK(655g), ♀ON x ♂ MK(605g) and ♀ON x ♂ ON(571g), ♀SK x ♂MK(605g), ♀SK x ♂ ON(553g) and ♀SK x ♂SK(501g). Based on the findings of this research, it can be concluded that improving performance of fish population through intraspecific crosses of fish strains from 53 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. different eco-regions is possible. It is therefore recommended, amongst others, that there is a need to produce the F2 and F3 generations, and even go further to add selection yield in genetic gains. Also, there is a need to do a comparative study of growth performance of fish raised out in hapas, concrete tanks and earthen ponds. Keywords: Pure breed, Cross breed, Hybridization, Germplasm, Progenies. Introduction Fish production through aquaculture is an age-long practice especially in Asia and Africa. For instance, production of the African catfishes Clarias gariepinus and Heterobranchus longifilis has been practiced for a long time in Africa (Adah et al., 2014). To ensure fish food security in Africa, increased production of fry and fingerlings with attributes of faster growth rates, high food conversion ratio and better environmental tolerance is greatly inevitable. Therefore, genetic techniques are needed to ensure the production of fish breeds with the aforementioned attributes. Heterobranchus longifilis is one of the most important species for aquaculture practices all over the world. Outside Africa, it is farmed in Europe, China, Brazil and India (Huisman and Richer, 1987, In: Olufeagba and Okomoda, 2015). There have been several attempts to improve its genetic performance through hybridization, chromosome manipulation, improved feeding and water quality management (Aluko, 1998, In: Olufeagba and Okomoda, 2015). One major strategy in preventing regression in growth is genetic improvement through selective breeding. Cross-breeding different strains of H. longifilis to select for better spawning performance, survival and long-term growth has a great potential in improving this species which is currently limited by poor growth and high cost of production (Olufeagba and Okomoda, 2015). Heterobranchus longifilis is generally considered to be one of the most important tropical catfish species for aquaculture. It has an almost Pan-African distribution, ranging from the Nile to West Africa and from Senegal to Tanganyika (Azeroual et al., 2010). In Nigeria, aquaculture is dominated by the Clariid fishes which are widely accepted and attracts high market value. The bane of the rapid development of aquaculture industry and stock management in Nigeria is the scarcity of genetically improved fish seed. There is therefore need to assess the genetic value of germplasm from different eco-regions and genetic gains that is possible from various mating combinations of this highly valued fish (Heterobranchus longifilis). Improving H. longifilis genetically in aquaculture is of great importance for so many reasons not only to improve production but also fast growth rate, marketability, culturability and the conservation of natural resources all year round. Mating combinations between strains from different eco-regions results in the production of improved offspring. The Agriculture Promotion Policy, 2016 - 2020, document,” The Green Alternative” enunciated by the Buhari Administration seeks to build an agribusiness economy capable of delivering sustained prosperity by meeting domestic food security goals, generating exports, and supporting sustainable income and job growth. In order to key into the objective of the “Green 54 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. Alternative”, this research is designed to produce a strong genetic base for Heterobranchus longifilis as fish seed. Nigeria faces significant food security challenges, with growing population and limited domestic food production. Fish is an essential source of protein in Nigerian diet, but the country relies heavily on imports to meet demand. The result, if adopted, proposes a sustainable fish production initiative to enhance food security and poverty alleviation in Nigeria. Materials and Methods Sexually mature strains of H. longifilis , were obtained from three eco-regions in Nigeria, namely; (1) Sahel Savanna at the Rima River in Sokoto (SK),(Lat.13.00590N, Long.5.24760 E), (2) Rainforest at the Niger River, Onitsha (ON) ( Lat., 6.13290N, Long.6.79240E) and (3) Guinea Savanna at the Benue River, Makurdi (MK), ( Lat,7.73220 N, Long.8.53910 E), respectively. The fish samples were transported live in 50 litres open black plastic jerry-cans with good aeration from the eco-regions to the Teaching and Research Farm of the Federal University of Agriculture, Makurdi and kept in earthen ponds. Six (6) earthen ponds of small size (5x5x1.5m3) were used for this purpose; each separately containing the male and the female fish samples from each of the eco-region. The fish samples were allowed two weeks to acclimatize. During this period, the fish were fed with 40% crude protein of fish feed for fattening. All the experiments were conducted at the Teaching and Research Farm of the Federal University of Agriculture, Makurdi. Three pairs each per sex per eco-region of similar size (2kg) were used for the breeding trials following the techniques adopted and reported by Ataguba et al.(2009) and Olufeagba et al.(2016). In brief, both sexes of the fish were injected with Ovaprim (Syndel, Canada) at the rate of 0.5ml/kg and maintained for latency period of 15h in separate tanks according to their sex and ecoregion. The eggs of the females from the same ecoregion were stripped into a bowl by applying light pressure on the abdominal part of the fish. The collected eggs from the females of the same ecoregion were then gently mixed using a chicken feather to make the eggs uniform. The male fish, conversely, were tranquilized using triacane methane sulphate (Wagner, et al,1997), before being euthanized to collect their testes. The milt from the testes of males of the same ecoregion was then used to fertilize the eggs from the same ecoregion, as well as eggs from the different ecoregions for both Parental and Intraspecific breeding experiments as shown below; Parental mating groups 1. Sokoto ♀H.longifilis(SK) X ♂H.longifilis (SK ) 2. Makurdi ♀H.longifilis(MK) X ♂H.longifilis(MK) 3. Onitsha ♀H.longifilis(ON) X ♂H.longifilis(ON) Intraspecific crosses 1.♀H.longifilis (SK) X ♂H.longifilis(MK) 2.♀H.longifilis(SK) X ♂H.longifilis(ON) 3.♀H.longifilis(MK) X ♂H.longifilis(SK) 55 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. 4.♀H.longifilis(MK) X ♂H.longifilis(ON) 5.♀H.longifilis(ON) X ♂H.longifilis(SK) 6.♀H.longifilis (ON) X ♂H.longifilis (MK) ♀ = female ♂ = male After mixing the milt with the eggs, the sperm cells were activated by addition of freshwater. Fertilized eggs were quickly spread across the already prepared triplicate hatching troughs (1 × 1 × 0.5m3) for each eco-region crosses for the incubation process of the egg. The eggs were maintained in this static system with continuous aeration until they were hatched. After hatching, direct counting of un-hatched eggs and those on the floor of the bowl was done. Hatched eggs were determined on the basis of the percentage of unhatched eggs. On the other hand, the percentage hatchability can be calculated using the equation below; % 𝐻𝑎𝑡𝑐ℎ𝑎𝑏𝑖𝑙𝑖𝑡𝑦 = 𝑁𝑜.𝑜𝑓 𝐻𝑎𝑡𝑐ℎ𝑙𝑖𝑛𝑔𝑠 𝑇𝑜𝑡𝑎𝑙 𝑁𝑜. 𝑜𝑓 𝐸𝑔𝑔𝑠 𝑋 100 Feeding of the fry commenced after the third day of hatching, firstly, with artemia for seven days and terminated, while indoor rearing continued in three replicates of 100 fry each in 50 litres plastic bowls, with feeding with 0.2mm Coppens. After two weeks of indoor rearing, the average percentage survival of each cross was determined. 50 fry from each parental and intraspecific crosses were transferred into hapas and reared outdoor in three replicates, and being fed continuously with various sizes of Coppens for 56 days. At this stage, the average weight of each cross was determined using a sensitive weighing balance and the average percentage survival of each cross was also determined. Also, in order to determine the true commercial application of the intra-generic crosses, following a recommendation by Ataguba et al (2010), samples of the fish of each cross were further reared in earthen ponds for nine months. The juveniles of each of the nine mating combinations were stocked in separate earthen ponds and reared until the development of their gonads; being sampled on monthly basis. During this period, their weights were taken monthly, using Mettler weighing balance and growth performance was evaluated based on Mean weight gain, Mean final weight and Specific Growth Rate. Results and Discussion Table 1, shows the percentage hatchability of fertilized eggs of pure and intraspecific crosses of H. longifilis. Our study shows that all the three pure line crosses of H. longifilis had high percentage hatchability (85%) which were not significantly different from each other. The least percentage hatchability is 63% in the intraspecific cross between ♀ON x ♂MK. Apochi(2016), also reported highest percentage hatchability (94.40%) in pure line Calabar cross of Clarias gariepinus. Since the least percentage hatchability is 63%, it agrees with the report of Viveen, et al, 1986, that in general, the mean percentage hatching of eggs should be between 50-80% for 56 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. successful breeding. The results obtained, therefore, provided a suitable platform for a successful breeding activity. Table 1: Percentage hatchability of pure and intraspecific crosses of strains H. longifilis from three eco-regions of Nigeria Crosses Hatchability (%) ♀SK x ♂SK 85.60 ± 6.97 ♀MK x ♂MK 85.00 ± 0.58 ♀ON x ♂ON 85.12 ± 3.87 ♀SK x ♂MK 83.00 ± 0.58 ♀SK x ♂ON 82.33 ± 0.33 ♀MK x ♂SK 70.00 ± 1.15 ♀MK x ♂ON 66.33 ± 0.33 ♀ON x ♂SK 84.33 ± 0.88 ♀ON x ♂MK 63.33 ± 1.76 p-value 2.31x 10-16 Fish egg hatchability could be attributed to several factors ranging from the intensity and stage of maturity of the parent stock. This is further buttressed by Blaster (1992), who stated that theoretically, apart from biological factors, physical and chemical parameters are known to affect egg development, for example; temperature is known to be the main environmental factor governing fish egg development. The result of this study shows higher percentage hatchability compared to the reported work of the De Graaf and Jansesen (1996), who reported percentage hatching of 59.1% in Clarias geriepinus, Aluko and Popoola (2002), reported highest percentage hatchability of 96.09% in the cross involving Kainji and Jos Heterobranchus longifilis, Jacob (2017) recorded highest percentage hatchability in the cross between female Common carp Ibadan and male Common carp Bauchi (53.65%). Moses et al, (2005) reported 58.58% hatchability in Kaniji strain of Clarias anguillaris. Hatchability percentage lower than 50% was reported by Nwadukwe (1995), who reported 4045% hatching success in H. longifitis. In addition, high percentage hatchability of 75 – 85% has been reported in H. longifilis by Lengendre et al; (1992). 57 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. The higher hatchability of the Sokoto strain might be as a result of egg quality. Kjorsvick (1991), observed that during mass rearing of marine fish larvae, variability in performance of eggs was attributed to egg quality. Table 2, shows the probability of survival by mating combinations of indoor rearing of H. longifilis at day 14. There was a significant difference between the percentage survival and mortality of all the mating combinations (p<0.05). Generally, there was low survival and high mortality rates in the indoor rearing of the hatchlings in plastic bowls. The pure line cross between ♀ON x ♂ON had the highest percentage survival (35%), followed by intraspecific cross between ♀MK x ♂ON (32.7%) and least for intraspecific cross ♀MK x ♂SK (23%). The result showed a significant difference between the survival probability of pure breeds and intraspecific breeds, with pure breeds having higher survival rate. Table 2: Survival probabilities of crosses of strains of H. longifilis reared indoor Crosses Initial Survivors Mortality Survival Probability ♀MK x ♂MK 300 80 220 0.267ab ♀MK x ♂ON 300 98 202 0.327ab ♀MK x ♂SK 300 69 231 0.230a ♀ON x ♂ON 300 105 195 0.350b ♀ON x ♂MK 300 71 229 0.237ab ♀ON x ♂SK 300 76 224 0.253ab ♀ SK x♂SK 300 70 230 0.233ab ♀ SK x♂MK 300 83 217 0.277ab ♀ SK x ♂ON 300 82 218 0.273ab Survival probabilities with different superscripts differ significantly(p<0.05) Table 3, shows the probability of survival by mating combinations of outdoor rearing of H. longifilis at day 56 (8wk). There was no significant difference between the percentage survival of all the mating combinations (p<0.05). The percentage survival for both pure line and intraspecific 58 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. crosses were quite high with comparatively corresponding low mortality. The intraspecific cross between ♀ON x ♂SK had the highest percentage survival (80%), followed by the intraspecific cross between ♀ON x ♂MK (78.3%) and least for the pure line cross ♀MK x ♂MK (73.3%). The result showed that the intraspecific crosses of Onitsha strain of H.longifilis had higher survival rates than its pure line cross; ( ♀ON x ♂SK = 80%, ♀ON x ♂MK = 78.3%, and ♀ON x ♂ON=75.0%). Table 3: Survival probabilities of crosses of strains of H. longifilis reared outdoor Crosses Initial Survivors Mortality Survival Probability ♀MK x ♂MK 60 44 16 0.733b ♀MK x ♂ON 60 45 15 0.750b ♀MK x ♂SK 60 46 14 0.766b ♀ON x ♂ON 60 45 15 0.738b ♀ON x ♂MK 60 47 13 0.783b ♀ON x ♂SK 60 48 12 0.800b ♀ SK x♂SK 60 46 14 0.767b ♀ SK x♂MK 60 45 15 0.750b ♀ SK x ♂ON 60 46 14 0.767b Survival probabilities not significantly different (p<0.05) Growth and survival are among the most important trait determining yield potential. Purdon (1986) reported that species evolve to maximize their chances of survival against a background of turmoil. He stressed further that domestication of any species of animal or plant is likely to find the turmoil replaced by order and constancy. In this study, there was significant difference in the survival of both parental and intraspecific crosses in indoor rearing. For indoor rearing, highest percentage survival (35.0%) was in the pure line cross between ♀ON x ♂ON while for outdoor rearing, the highest percentage survival (80.0%) was in the intraspecific cross between ♀ON x ♂SK . For parental crosses, Makurdi strain had the highest percentage survival (35.0%) for indoor rearing while Sokoto strain had the highest percentage survival (76.7%) for outdoor rearing. This result is at variance with the work of Apochi (2016) who reported that there were no significant differences in the survival of both the indoor and 59 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. outdoor rearing of parental and intraspecific crosses. This result, also, has proven the hybrid vigor as expected from intraspecific hybridization. The pure line parental cross of Sokoto had the highest percentage hatchability (85.6%) but low survival rate (23.3%) for indoor rearing. However, its intraspecific cross with Onitsha strain yielded the highest percentage survival (80.0%) for outdoor rearing. The higher survival value recorded in the cross between parental Onitsha strain for indoor rearing and its intraspecific cross with Sokoto strain for outdoor rearing might be due to good survival trait of Onitsha strain. Mustapha and Rahman (1999) also stated that intra-population genetic diversity provides a range of genotype, thereby presenting more opportunities for survival and evolution under changing environmental conditions. Lamai (1999) reported 52.5%; 40% by Madu et al; (1991) and 25.4% by Sule (1991) survival for Clarias gariepinus. The low survival value in all the mating combinations for indoor rearing might be due to fluctuating temperature, inadequate conversion of feed by fry, medium of rearing and other likely variables. Brenda and Riley (1981) observed that the survival of larvae beyond yolk stage is dependent on the provision of a suitable food source as they have no built in reserve of food. Table 4 shows the mean initial weight (MIW), mean final weight ( MFW), mean weight gain (MWG), percentage weight gain (%WG) and specific growth rate (SGR) for pure breeds and cross breeds of three strains H. longifilis from different eco-regions of Nigeria , reared under hatchery conditions in plastic bowls for 14days. The pure breed, ♀MK x ♂MK, showed lower weight gain (81.2%) than its cross breed ♀MK x ♂ON (86.2%) and ♀MK X ♂SK(82.3%). The growth rates of the two intraspecific hybrids ♀MK x ♂ON and ♀MK X ♂SK were significantly higher than that of the pure breed ♀MK x ♂MK . In terms of mean final weight, the cross breed ♀MK x ♂ON had a significantly higher weight (0.102g), (P<0.05) than the other cross breed and the pure line cross. The cross breed ♀ONx♂MK had a significantly (P<0.05) higher weight gain (83.39%) than the other crosses; ♀ONx♂ON (82.76%) and ♀ONx♂SK (82.57%). The growth rate of the cross breed ♀ONx♂MK was significantly (P<0.05) higher than the other cross breed ♀ONx♂SK and pure line cross ♀ONx♂SK. Though higher, the growth rate between pure line cross ♀ONx♂ON and cross breed ♀ONx♂SK was not significantly different (P<0.05). Generally, the growth rates of the cross breeds were significantly higher than the pure breeds. In terms of mean final weights, the cross breed ♀MKx♂ON had a significantly (P<0.05) higher weight than the other eight crosses. The pure breeds do not have close SGR; 0.119, 0.125 and 0.116 for ♀MKx♂MK, ♀ONx♂ON and ♀SKx♂SK, respectively. The cross breed ♀MKx♂ON had the highest weight gain (86%) which was significantly different from all other crosses. Growth pattern is similar for all the crosses (Figure 1). Table 4: Variations of Growth Parameters of indoor rearing of pure line and cross breeds of strains of H. longifilis from Day 4 after hatching for 14 days Growth Parameters 60 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. Copyright ©SIAR Publications. All rights Reserved. Means on the same column with different superscript are statistically significant (p<0.05) Mating Combinations MIW(g) MFW(g) MWG(g) %WG SGR(g) FCR(g) ♀MK X ♂MK 0.014±0.00 0.075±0.00de 0.061±0.01de 81.290±0.64de 0.119±0.00de 0.006±0.00bcd ♀MK X ♂ON 0.014±0.00 0.102±0.00a 0.088±0.00a 86.274±0.07a 0.141±0.00a 0.004±0.00e ♀MK X ♂SK 0.014±0.00 0.079±0.01cd 0.065±0.00cd 82.343±0.29bcd 0.123±0.00bcde 0.006±0.00bcd ♀ON X ♂MK 0.013±0.00 0.084±0.00bc 0.070±0.00bc 83.394±0.74bc 0.128±0.00bc 0.006±0.00bcd ♀ON X ♂ON 0.014±0.00 0.079±0.00cd 0.065±0.01cd 82.760±1.18bcd 0.125±0.00bcd 0.005±0.00cd ♀ON X ♂SK 0.014±0.00 0.080±0.00cd 0.066±0.00cd 82.572±0.07bcd 0.124±0.00bcd 0.006±0.00bcd ♀SK X ♂MK 0.014±0.00 0.078±0.00d 0.064±0.00d 81.784±0.26cde 0.121±0.00cde 0.006±0.00bcd ♀SK X ♂ON 0.014±0.00 0.089±0.02b 0.074±0.01b 83.871±0.63b 0.130±0.00b 0.006±0.00bcd ♀SK X ♂SK 0.013±0.00 0.070±0.00e 0.056±0.01e 80.394±0.73bc 0.116±0.01e 0.007±0.00a P-value - <0.01 <0.01 <0.01 <0.01 <0.01 67 Official Publication of the Society of Innovative Academic ResearchersSIAR PUBLICATIONS Advancing Real-Time Innovative Knowledge Globally. 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